The essentials of histology : descriptive and practical, for the use of students.

  • Sharpey-Schäfer, E. A. (Edward Albert), Sir, 1850-1935.
Date:
1885
Catalogue details

Licence: Public Domain Mark

Credit: The essentials of histology : descriptive and practical, for the use of students. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    The Sylvian aqueduct (s), with its lining of ciliated epithelium, re- presents the central canal of the cord and the fourth ventricle of the medulla. In the grey matter which surrounds it {central grey matter) there is seen in all sections of the region a group of large nerve-cells lying anteriorly on each side of the middle line, close to the reticular formation. From this group the root-bundles of the fourth nerve arise at the lower part of the mesencephalon and pass obliquely backwards and downwards around the central grey matter, decussating with those of the opposite side to emerge just above the pons Varolii (fig. 234). Higher up the bundles of the third nerve spring from the continuation of the same nucleus (fig. 235, n. ///.), and these pass forwards and down- wards with a curved course through the reticular formation, to emerge at the mesial side of the crusta. The reticular formation of the pons is continued up into the mes- encephalon, and is here known as the tegmentum. It is composed as before of longitudinal and transverse bundles of fibres with much grey matter intermingled. The transverse fibres include the decussating fibres of the superior crura of the cerebellum {s.c.j).), and the fibres of the fillet (/), which are passing in an oblique manner from the raphe to the side of the mesencephalon, to reach eventually the grey matter of the prominences of the corpora quadrigemina. The pyramid bundles of the pons are continued upwards on each side into the crusta (cr.). This forms a mass of longitudinally coursing bundles of fibres lying on the ventral aspect of each half of the mesencephalon, and diverging above into the internal capsule of the cerebral hemisphere. The crusta is separated from the tegmentum by a layer of grey matter containing a number of very deeply pigmented nerve-cells which give it the name of substantia nigra (s.n.) The crusta and tegmentum, together with the intervening substantia nigra, constitute the cms cerebri. The prominences of the corpora quadrigemina are formed mainly of grey matter containing numerous small nerve-cells. From each a bundle of white fibres (brachium) passes upwards and forwards towards the geniculate bodies, eventually joining the optic tract of the same side. On the other hand, each of the prominences receives from below fibres of the fillet, which are themselves traceable into the posterior part of the lateral column of the medulla oblongata.